JP7152636B2 - Communication device and communication method - Google Patents

Description

The present invention relates to a communication device and communication method suitable for application to, for example, collecting big data.

In recent years, progress has been made in the construction of systems that create new value by accommodating all kinds of things through wireless communication and collecting and analyzing huge amounts of information (big data). One of the most important issues in this system is how to construct a wireless network that comprehensively collects information. Public wireless lines such as LTE (Long Term Evolution) and public wired lines can be used if they are available, but such public wireless lines are used due to cost, security, and required communication volume. can be difficult to do. Alternatively, the system may be operated outside of the physically available area in the first place. In this case, it is necessary to build a wireless network that can cover a wide area as a private wireless network. It is necessary to build a relay network. For example, Patent Literature 1 describes a technique related to big data analysis.

JP 2016-076217 A

In a large-scale wireless relay network that collects big data, the required communication volume generated by each terminal (each base station or each relay station) changes moment by moment. The problem is whether the number of communication frames, etc.) should be allocated.

Another issue in constructing a large-scale wireless relay network is determining which terminals (base stations) are to be relayed and the relay route. Currently, the terminals (base stations) that are turned on participate in the network in order, but there are many cases in which the route is not optimal for the entire network, which is a problem. Also, if there is a limit to the number of child base stations that each base station can accommodate, there is a risk that some base stations will not be able to participate in the network in the first place.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a communication apparatus and communication method that enable optimal allocation of radio resources and optimal routes.

In the present invention, a wireless network is configured by one or more subtrees including subroot stations,
The sub-root station collects the requested radio resource allocation information possessed by the child stations included in the sub-tree, receives the sum of the requested radio resource allocation information of the sub-root station itself to the allocation request information, and sends the sub-tree to the sub-root station. It is a communication device that notifies the radio resource information that can be used as a whole.
Also, the present invention is a communication method for performing such processing.
The present invention is a communication device that allocates radio resources to a sub-root station and child stations based on radio resource information notified to the sub-root station.
Also, the present invention is a communication method for performing such processing.
The present invention calculates the amount of radio resources required for unit data transmission between connectable stations,
Calculate the amount of E2E (End-to-End) required radio resources between the collection base station and each relay station;
This is a communication device that selects a route that minimizes the radio resource amount obtained.
Also, the present invention is a communication method for performing such processing.

According to at least one embodiment, it is possible to flexibly allocate radio resources in response to the ever-changing amount of communication demanded by each terminal (or base station or relay station). In addition, based on the information of each terminal (or base station or relay station) collected by the server that manages the network and information such as communication quality between each link, which terminal (or base station or relay station) is connected Then, an efficient wireless relay network can be constructed, or the relay route can be automatically generated. Furthermore, by repeatedly performing the radio resource allocation according to the present invention and the route selection according to the present invention, it is possible to flexibly respond to ever-changing communication conditions and communication requirements of each terminal (or base station or relay station) that constitutes the network. It is possible to realize the optimum wireless relay network condition. Note that the effects described herein are not necessarily limited, and may be any effect described in the present invention or an effect different from them. Also, the effects illustrated in the following description should not be construed as limiting the content of the present invention.

FIG. 1 is a schematic diagram showing an outline of a wide-area Wi-RAN to which the present invention can be applied. FIG. 2 is a block diagram showing a schematic configuration of a collection base station. FIG. 3 is a block diagram showing a schematic configuration of a relay station. FIG. 4 is a flowchart showing the overall flow of processing. 5A to 5C are schematic diagrams used to describe types of radio resource allocation. FIG. 6 is a flowchart showing the flow of radio resource allocation processing. FIG. 7 is a flowchart showing the flow of radio resource allocation processing. FIG. 8 is a schematic diagram for explaining an example of radio resource allocation processing. FIG. 9 is a flowchart showing the flow of radio resource allocation processing. FIG. 10 is a schematic diagram for explaining an example of radio resource allocation processing. FIG. 11 is a flowchart showing the flow of radio resource allocation processing. FIG. 12 is a schematic diagram for explaining an example of radio resource allocation processing. FIG. 13 is a schematic diagram of an example of a wireless network system. 14A and 14B are schematic diagrams for explaining IDs added to each station. FIG. 15 is a schematic diagram showing an example of traffic volume demanded by each station. FIG. 16 is a schematic diagram showing an example of radio resource allocation. FIG. 17 is a schematic diagram used to explain the US radio resource allocation procedure. FIG. 18 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 19 is a schematic diagram used to explain the US radio resource allocation procedure. FIG. 20 is a schematic diagram used to explain the US radio resource allocation procedure. FIG. 21 is a schematic diagram used to explain the US radio resource allocation procedure. FIG. 22 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 23 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 24 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 25 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 26 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 27 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 28 is a schematic diagram used to describe a US radio resource allocation procedure. FIG. 29 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 30 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 31 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 32 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 33 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 34 is a schematic diagram used for explaining the DS radio resource allocation procedure. FIG. 35 is a schematic diagram used for explaining the DS radio resource allocation procedure. FIG. 36 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 37 is a schematic diagram used to explain the DS radio resource allocation procedure. FIG. 38 is a schematic diagram used for explaining a route selection algorithm. FIG. 39 is a schematic diagram used for explaining a route selection algorithm. FIG. 40 is a schematic diagram used for explaining a route selection algorithm. FIG. 41 is a schematic diagram used for explaining a route selection algorithm. FIG. 42 is a schematic diagram used for explaining a route selection algorithm. FIG. 43 is a schematic diagram used for explaining a route selection algorithm. FIG. 44 is a flowchart used to explain the route selection algorithm. FIG. 45 is a schematic diagram used for explaining a route selection algorithm. FIG. 46 is a schematic diagram used for explaining a route selection algorithm. FIG. 47 is a schematic diagram used for explaining a route selection algorithm. FIG. 48 is a schematic diagram used for explaining a route selection algorithm.

The embodiments described below are preferred specific examples of the present invention, and are subject to various technically preferable limitations. However, the scope of the present invention shall not be limited to these embodiments in the following description unless specifically stated to limit the present invention.
It should be noted that the present invention will be described in the following order.
<1 Embodiment of the Present Invention>
<2 Modifications>

<1 Embodiment of the Present Invention>
An embodiment of a communication device and a communication method according to the present invention will be described below with reference to the drawings. FIG. 1 shows a wide area wireless communication system (hereinafter referred to as a wide area Wi-RAN (Wireless Regional Area Network)) for collecting big data, for example. The classifications and functions of the constituent terminals are as shown in Table 1 below. The present invention is applied to communications using backbone lines in such Wi-RAN.

In Table 1, Wi-SUN (Wireless Smart Utility Network) (registered trademark) is a radio communication standard that uses a radio frequency band called specified power-saving radio or Sub-GHz. It corresponds to the 920 MHz band in Japan.

An outline of this wide-area Wi-RAN is shown below.
It has a tree topology structure.
Downstream (denoted DS): multiple access from one collection base station (BS, BS-S, BS-L, or BS-LS) to multiple relay stations (RS or RS-S)
Downlink (DL): Downlink station-to-station communication

Upstream (denoted as US): Multiple relay stations have multiple accesses to the upper relay station, and the final destination is only one or more collecting base stations. Uplink (UL): Uplink inter-station communication BS is , is a wide-area Wi-RAN root station and is a wireless device that can connect to the Internet or cloud through a private line. BS-S is a wide-area Wi-RAN root station and is a wireless device that can be connected to the Internet or cloud through a private line. and has a bridge function with a local data collection network such as Wi-SUN or a collection base station function for a local data collection network such as Wi-SUN BS-L is a root station of wide area Wi-RAN BS-LS is a wide-area Wi-RAN root station, and is a wireless device that can connect to the Internet or cloud through an LTE line or a private line. Furthermore, a radio RS having a bridge function with a local data collection network such as Wi-SUN or a collection base station function for a local data collection network such as Wi-SUN is a radio RS having a relay function of Wi-RAN. -S is a wireless device having a Wi-RAN relay function, and further has a bridge function with a local data collection network such as Wi-SUN or a collection base station function for a local data collection network such as Wi-SUN. wireless device

FIG. 2 shows a schematic configuration of a collection base station (collection base station BS, collection base station BS-L, etc. in FIG. 1). The collection base station 10 has a radio processing section 11 and a scheduler server 21 . The radio processing unit 11 includes a high frequency processing unit 12 and a baseband processing unit 13 for radio communication. A scheduler server 21 is provided for the wireless processing unit 11 . The scheduler server 21 controls radio resource allocation and route selection. Radio resource allocation is controlled by the radio resource request amount collection and analysis unit 22 and the radio resource allocation calculation unit 23 . Route selection is controlled by the line quality information collection/analysis section 24 and the optimum relay route calculation section 25 for each relay station/relay link. In this specification, radio resources mean network radio resources.

FIG. 3 shows a schematic configuration of a relay station (relay station RS, relay station RS-S, etc. in FIG. 1). The relay station 30 has a radio processing section 31 and a relay control section 41 . The radio processing unit 31 includes a high frequency processing unit 32 and a baseband processing unit 33 for radio communication. A relay control unit 41 is provided for the wireless processing unit 31 . The relay control unit 41 controls radio resource allocation and route selection. A radio resource allocation unit 42 and a connection unit 43 with a collection system are provided for controlling radio resource allocation. It has a route switching unit 44, a line quality sensing unit 45, a radio resource allocation instructing unit 46, and a route switching instructing unit 47 for controlling route selection.

"Overview of radio resource allocation processing"
FIG. 4 is a flow chart showing the overall flow of radio resource allocation processing in one embodiment of the present invention, and the following processing is performed.
Step S1: The scheduler server is powered on.
Step S2: The collection base station is powered on.
Step S3: The relay station is powered on.

Step S4: It is determined whether the beacon from the collection base station is visible.
Step S5: When it is determined that the beacon is visible, the radio resource allocation algorithm is processed.

Step S6: If it is determined in step S4 that the beacon is not visible, it is determined whether the beacon from the relay station already connected to the collecting base station is visible.
Step S7: If it is determined in step S6 that the beacon is not visible, the relay station waits.
Step S8: It is detected that a change in radio channel conditions, entry of a new relay station, or the like has occurred. In this case, the process returns to step S5 (process of radio resource allocation algorithm).

"Radio Resource Allocation"
In the radio resource allocation, the (US (Up Stream)/DS (Down Stream) ratio) varies depending on the system to be used. FIG. 5A shows US-focused radio resource allocation. Suitable for systems with large US requirements. The DS quota is determined according to the US quota. FIG. 5B shows DS-focused radio resource allocation. It is suitable for systems that require a large amount of DS. The US quota is determined according to the DS quota. FIG. 5C shows both US and DS-oriented radio resource allocation. This is suitable for systems in which the US request amount and the DS request amount are about the same. Determine the DS and US quotas separately. As an example, radio resources include frequency-related radio resources, time-axis-related radio resources, and the like. In FIG. 5, for example, the vertical axis represents frequency-related radio resources, and the horizontal axis represents time-related radio resources. The radio resource allocation amount is represented by the area of the rectangular area.

"Handling Radio Resource Allocation"
FIG. 6 is a flowchart showing an example of the flow of radio resource allocation processing, in which the following processing is performed.
Step S11: The US/DS ratio is determined.
Step S12: It is determined whether it is a US type (US-oriented type).
Step S13: In step S12, if it is determined to be the US type, the US requested radio resource amount is obtained.
Step S14: US allocated radio resources are determined.
Step S15: Determine DS-assigned radio resources in the same proportion as US-assigned radio resources.

Step S16: If it is determined in step S12 that it is not the US type, it is determined whether it is the DS type (DS-oriented type).
Step S17: In step S16, if it is determined to be the DS type, the DS requested radio resource amount is acquired. Also, DS allocated radio resources are determined.
Step S18: Determine US-assigned radio resources in the same proportion as DS-assigned radio resources.

Step S19: If it is determined in step S16 that it is not the DS type, the US requested radio resource amount is acquired.
Step S20: US allocated radio resources are determined.
Step S21: The amount of radio resources requested by the DS is obtained, and the allocated radio resources for the DS are determined.
The processing of the flowchart shown in FIG. 6 is periodically repeated.

"Acquisition of requested radio resource amount in US"
FIG. 7 is a flow chart showing an example of the flow of processing for acquiring the requested radio resource amount in the US, and the following processing is performed. Also, FIG. 8 shows a specific example of a subtree when "AA" is a subroot station. The subtree in this specific example consists of "AA", "AAA", "AAB", "AAAA", and "AAAB".

Step S31: Acquisition of requested radio resource amount of own station.
Step S32: It is determined whether or not there is a new entry station.
Step S33: If it is determined in step S32 that there is a new entry station, a new entry frame is allocated (any size).

Step S34: It is determined whether or not there is a child station.
Step S35: If it is determined in step S34 that there is a child station, the required radio resource amount for each child station is acquired.
Step S36: Request the master station for the sum of the radio resource amount requested by the local station and the radio resource amount requested by the child station.
Step S37: Store the ratio or absolute value of the radio resource amount requested by each station.
Step S38: When it is determined in step S34 that there is no slave station, the master station is requested to request the radio resource amount of the own station. Then, the process moves to step S37.

In FIG. 8, "A" or "B" represents the station ID. When "AA" is a sub-root station, "AAA" and "AAB" are child stations. Since the requested radio resource amount of the own station for "AAA" is "2" and the requested radio resource amount of the child station for "AAA" is "6", "AAA" is "the requested radio resource amount of the own station. + Requested radio resource amount of slave station = 2 + 6 = 8". Regarding "AAB", it is assumed that "required radio resource amount of own station + requested radio resource amount of child station = 4 + 2 = 6". Therefore, in "AA", "required radio resource amount of own station + requested radio resource amount of child station = 4 + 8 + 6 = 18". "AA" requests "18" from the parent station.

"Determination of US Assigned Radio Resources"
FIG. 9 is a flowchart showing an example of the flow of US allocation radio resource determination processing in the radio resource allocation determination processing, and the following processing is performed. Also, FIG. 10 shows a specific example of a subtree when "AA" is a subroot station. The subtree is composed of "AA", "AAA", and "AAB".

Step S41: Acquire the US allocation for the subtree with the own station as the top from the parent station. Step S42: Allocate radio resources according to the ratio or absolute value of the amount of radio resources requested by the child station and the own station, and notify the child station.

FIG. 10 shows an example of a subtree when "AA" is the subroot station. Assume that 36 radio resources for US are allocated from “A” (the parent station of AA). The radio resources allocated from this "A" are allocated at a ratio of (4:8:6), that is, 8 radio resources are allocated for "AA", 16 radio resources are allocated for "AAA", and "AAB , 12 radio resources are allocated. Notify the slave stations of these assignments. Examples of absolute values are number of bytes, number of frames, and the like.

"Processing of Acquisition of DS Requested Radio Resource Amount/Determination of DS Assigned Radio Resource"
FIG. 11 is a flowchart showing an example of the flow of processing for obtaining the amount of radio resources requested by the DS and determining the radio resources to be allocated to the DS in the radio resource allocation determination processing, and the following processing is performed. Also, FIG. 12 shows a specific example of a subtree when "AA" is the subroot.
Step S51: The collection base station grasps the amount of DS traffic destined for each station, and allocates radio resources to child stations according to the ratio or absolute value of the amount of traffic. The absolute value is the number of bytes, the number of frames, and so on.
Step S52: Allocate radio resources to child stations by excluding those for the own station from the radio resources allocated by the parent station.

FIG. 12 shows an example of a subtree when "AA" is the subroot station. The subtree is composed of "AA", "AAA", and "AAB". "AA" as a sub-root station grasps the traffic volume (eg, 10) of "AAA" as a child station and the traffic volume (eg, 4) of "AAB" as a child station.

"AA" receives from "A" (AA's parent station) that 16 has been allocated as a radio resource for DS. "AA" allocates 14 excluding the radio resource (2) addressed to itself according to the ratio (10:4) or absolute value of the DS traffic volume of the child station.

"Description of Radio Resource Allocation"
Radio resource allocation in one embodiment of the present invention will be described in more detail. The control of radio resource allocation described below is basically the same as that described above. An example of a wireless network system is shown in FIG. The radio network is called TD/MM (Top-Down and Middle Management) type TDD two-way multi-pop.

As an example, it has layers from the first layer to the fourth layer. A letter attached to each station represents a station ID. As shown in FIG. 14A, for example, the upper "AA" of the station ID of "AAA" indicates the ID of the parent station (indicated as Parent in the figure), and the lower "A" indicates the sibling station (indicated as Parent in the figure). is written as Sibling). For example, "AAA" and "AAB" are sibling stations. Furthermore, "ABA" indicates a cousin station (denoted as Cousin in the figure). A subtree is represented by connecting triangles with a certain station as a vertex. FIG. 13 shows a subtree with "AAA" as the subroot station.

An outline of basic operation will be described.
A resource block (radio resource allocation unit) is assigned to each link.
The basic operation in each subroute is as follows.
1. The sub-root station collects each layer requested radio resource allocation information of each child station.
2. The requested radio resource allocation information of the sub-root station itself is added to the collected information and reported to the master station.
3. Each layer radio resource information that can be used in the entire subtree is distributed from the master station to the subroot station.
4. Allocate the above-mentioned allocated radio resources to the sub-root station itself and child stations. Each station includes the amount of radio resources for new entrant stations in its own radio resource request amount.

There are three methods of allocating radio resource blocks.
The first method divides links in the same hierarchy in the frequency direction. Links in different layers are divided in the time direction.
The second method divides each link only in the time direction without dividing into subcarriers (frequency direction).
A third method divides each link into frequency and time directions.

"Specific example of radio resource allocation"
FIG. 15 shows an example of the amount of traffic requested by each station in the wireless network system shown in FIG. As shown in FIG. 14B, for example, "2" in the numbers (2/1, 3) added to the left side of the "AA" station box represents the US requested traffic volume, and "1" It represents the amount of DS traffic requested for station A, which is a child station (indicated as Child in the figure), and "3" represents the amount of DS traffic required for station B, which is a child station. Also, "→2" added to the right side of the box represents the amount of traffic destined for the AA station, and "←4" represents the amount of traffic generated by the AA station and requested by the own station.

The result of radio resource allocation corresponding to the example shown in FIG. 15 is shown in FIG. In FIG. 16, the horizontal axis represents time (TDD) slots, and the vertical axis represents the logical allocation block size. Also, radio resource allocation is made to each of US and DS between stations in different hierarchies. The procedures for such radio resource allocation will be described in order below.

"US radio resource allocation procedure (1-1)"
Each sub-root station collects the total amount of US traffic requested at each layer of its own sub-tree and reports it to the parent station. FIG. 17 shows an example in which the sub-root station of the fourth layer collects the total US traffic volume value of its own subtree and reports it to the parent station of the third layer.

"US radio resource allocation procedure (1-2)"
Each sub-root station collects the total amount of US traffic requested at each layer of its own sub-tree and reports it to the parent station. FIG. 18 shows an example in which the third layer subroot station collects the total US traffic volume value of its own subtree and reports it to the second layer parent station.

"US radio resource allocation procedure (1-3)"
Each sub-root station collects the total amount of US traffic requested at each layer of its own sub-tree and reports it to the parent station. FIG. 19 shows an example in which a layer 2 subroot station collects the total US traffic volume value of its own subtree and reports it to the layer 1 parent station.

"US radio resource allocation procedure (2-1)"
The root station/each sub-root station notifies its own child station of the frequency direction RB number ratio/permutation of the US allocated radio resources in each layer of the sub-tree. FIG. 20 shows a specific example of the RB number ratio/permutation notified. 21 and 22 represent the processing of this notification in order.

"US radio resource allocation procedure (2-2)"
The root station/each sub-root station notifies its own child station of the frequency direction RB number ratio/permutation of the US allocated radio resource in each layer of the sub-tree. FIG. 23 shows a specific example of the RB number ratio/permutation notified. 24, 25 and 26 represent the processing of this notification in order.

"US radio resource allocation procedure (2-3)"
The root station/each sub-root station notifies its own child station of the frequency direction RB number ratio/permutation of the US allocated radio resource in each layer of the sub-tree. FIG. 27 shows a specific example of the notified RB number ratio/permutation. FIG. 28 represents the processing of this notification in order.

"DS radio resource allocation procedure (1)"
Ascertain the amount of DS traffic destined for each station at the collection base station

"DS radio resource allocation procedure (2-1)"
The root station/each sub-root station notifies its child station of the frequency direction RB number ratio/permutation of the DS-assigned radio resources in each layer of the sub-tree. FIG. 29 shows a specific example of the RB number ratio/permutation notified. 30 and 31 represent the processing of this notification in order.

"DS radio resource allocation procedure (2-2)"
The root station/each sub-root station notifies its own child station of the frequency direction RB number ratio/permutation of the DS-assigned radio resources in each layer of the sub-tree. FIG. 32 shows a specific example of the RB number ratio/permutation notified. 33, 34 and 35 sequentially represent the processing of this notification.

"DS radio resource allocation procedure (2-3)"
The root station/each sub-root station notifies its own child station of the frequency direction RB number ratio/permutation of the DS-assigned radio resources in each layer of the sub-tree. FIG. 36 shows a specific example of the notified RB number ratio/permutation. FIG. 37 represents the processing of this notification in order.

"Description of route selection"
Route selection in one embodiment of the present invention will now be described in more detail. Note that "new entry" means that a station is newly added to the network. "Modulation scheme switching" is a process of changing MCS (Modulation coding scheme) depending on the situation. “Route selection” is control for planning a route based on the MCS so as to reduce the overall required radio resources. An example of selectable MCS is shown in Table 2 below.

In one embodiment of the present invention, both control of route selection and control of radio resource allocation are repeatedly performed. Comparing both controls, the frequency of control of radio resource allocation is higher than the frequency of control of route selection.

One of the goals of route selection is that each relay station performs multi-hop transmission and reception with a small amount of radio resources, thus reducing the radio resource usage required in the entire network. That is, in order to increase the amount of transmission per unit radio resource, a route with a high transmission speed (a route with a small amount of required radio resource) is selected. Another goal is to reduce the number of hops and improve controllability. If there is no increase in the amount of required radio resources, a station (upper station) with a small number of hops to the collection base station is selected. Note that, in one embodiment of the present invention, there is a limit to the number of devices that can be connected. For example, a station such as each RS can connect to three or less slave stations. The station to be connected is selected according to the amount of load increase. The reason for limiting the number of slave stations that can be connected is to communicate a large amount of data through the trunk line. The above limit number of connections "3" is just an example and can be set arbitrarily.

"Route Selection Algorithm"
In the case of a new entry, search for surrounding stations and connect to the found station.
In the case of route selection, all routes are constructed based on information on connectable stations and required radio resource amount information between those stations. If the established route exceeds the maximum number of connectable stations, reestablish

The processing flow of the route selection algorithm will be described with reference to FIG.
Step S61: Arrange stations Step S62: Calculate the amount of radio resources required for unit data transmission between connectable stations.
Step S63: Calculate the amount of required radio resources for E2E (End-to-End: path connecting two parties) from the collection base station to each relay station.

Step S64: Each relay station selects the minimum route.
Step S65: It is determined whether or not there is a relay station to which four or more relay stations are connected.
Step S66: If it is determined in step S65 that there are four or more relay stations, reconstruction is performed.
Step S67: If it is determined in step S65 that the number of relay stations is less than four, route selection is completed. Note that the threshold value (4) is an example, and other values may be used.

The flowchart of FIG. 39 shows the order of priority when determining the connection destination in step S64.
Step S71: A route with a smaller E2E required radio resource amount Step S72: If the values are the same, a route with a smaller number of hops to the collection base station Step S73: If still one cannot be selected, the requested radio resource amount before route change path with small

"Method for calculating required E2E radio resource amount"
Calculate the amount of required radio resources required when a unit packet passes through each link. Note that the required amount of radio resources is the amount of radio resources required when a unit packet passes through the link. The following example shows a case where the amount of radio resources is considered in terms of the number of communication frames.
In the example of FIG. 40, when station C transmits to station A, (station C → station B) requires 2 frames and (station B → station A) requires 4 frames, for a total of 6 frames. necessary.
When station E participates in the tree, the links with parent station candidate stations C and D are in the same hierarchy, two frames are required between EC and ED, and the connection destination (parent station) is determined. Can not do it.

As shown in FIG. 41, the required number of frames for each link is added. In FIG. 41, numbers in bold letters represent the total number of frames from the corresponding station to station A. In FIG. Therefore, if station E transmits to station A via station C, (2+2+4=8) frames are required, and if station E transmits to station A via station D, (2+3+4= 9) A frame is required. Therefore, station E is determined to be best if parented to station C, which requires a smaller number of frames.

The MCS (see Table 2 above) is determined from the CINR (Carrier to Interference and Noise Ratio). For example, the MCS is determined from the CINR average value. Dispersion may also be considered. Additionally, values other than average values may be used. Once the MCS is determined, the transmission rate can be calculated from the MCS. FIG. 42 shows an example of the relationship between CINR and transmission speed. It is also possible to calculate the transmission rate from the CINR. The number of frames required for unit data transmission calculated from the transmission speed information is used for route selection. In addition to CINR, other indices representing line quality such as RSSI (Received Signal Strength Indication/Indicator) may be used.

The relationship between the MCS switching cycle and the path switching cycle is (MCS switching cycle<path switching cycle). It should be noted that the MCS is allowed to switch within the path switching period. Frequent MCS switching is not required.

Furthermore, FIG. 43 shows an example of transmission rate variation, and calculation of the required number of frames will be described with reference to FIG. The number of frames is calculated based on the transmission rate for each path switching cycle. A high transmission speed means a small number of required frames. Consider the transmission rate from the previous path switching timing to the present. In other words, it is easy to be affected by instantaneous fluctuations if the decision is made based only on the latest transmission rate. For example, the number of required frames is calculated from the average transmission speed and used for route selection.

Reconstruction rules in the route selection algorithm are explained.
"Rule 1": If there is only one connectable master station, the connection is given the highest priority. This is because communication is not possible if there is no connection.
"Rule 2": Assuming that the slave station candidate is not connected, the station with the smallest increase in the number of required frames compared to the time of connection is excluded from the slave station candidates.
Also, when one connected station candidate is deleted, the route selection flow is executed again in the deleted state.

Processing as shown in the flow chart of FIG. 44 is performed.
Step S81: It is determined whether or not there is a station with only one connectable station.
Step S82: If the determination result of step S81 is yes, exclude the station from consideration for reconstruction.
Step S83: The increment of the required E2E frame number when the partner with the second smallest required E2E frame number is selected is calculated.
Step S84: The station with the smallest increment is excluded from the connectable stations.
Step S85: Return to the E2E required frame number calculation in the route selection flow.

"An example of how the route selection algorithm works"
An operation example of the route selection algorithm shown in the flowchart of FIG. 38 will be described. FIG. 45A shows the result of step S62 (calculation of required number of frames) in the flow chart. In FIG. 45, dashed paths represent connectable paths, and solid paths represent connected paths. The number attached to each pass in FIG. 45A represents the required number of frames per unit data in that pass. Such notation is the same in other drawings.

The processing result of step S63 (calculation of the number of E2E frames from the collection base station to each relay station) is shown in FIG. 45B. Station A is the collection base station, and the numbers in bold represent the required number of frames per unit of data up to the collection base station. Such notation is the same in other drawings.
The path shown in FIG. 45C is formed by the process of step S64 (each relay station selects the minimum path).

An example of reconstruction will be described with reference to FIG. "Rule 1" with respect to reconstruction described above applies. In the example of FIG. 46, station E can only parent station C because of "Rule 1". Station C connects to station E as a slave station.

An example of reconstruction will be described with reference to FIG. "Rule 2" regarding reconstruction described above applies. "Rule 2" is "assuming a case where the slave station candidate is not connected, excludes from the slave station candidates the station with the smallest increase in load compared to when it was connected." Let "load" be "the number of E2E frames required to the collection base station". In the example of FIG. 47, when station B is not connected to station C, the required number of E2E frames to the collection base station changes from 2 to 3 (required frame number increase: 1).

FIG. 48A, like FIG. 47, shows the amount of increase in the required number of frames when station B is excluded. FIG. 48B shows an increase of "2" in the required number of frames when station D is excluded. FIG. 48C shows an increase of "4" in the required number of frames when station F is excluded. Therefore, in the examples of FIGS. 47 and 48, it is optimal to exclude station B from the child station candidates.

<2 Modifications>
Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications are possible based on the technical idea of the present invention. Also, the configurations, methods, steps, shapes, materials, numerical values, etc. of the above-described embodiments can be combined with each other without departing from the gist of the present invention.

10... collection base station, 11... radio processing unit, 21... scheduler server, 22... radio resource request amount collection/analysis unit, 23... radio resource allocation calculation unit, 24... line Quality information collection and analysis unit 25 Optimum relay route calculation unit 30 Relay station 31 Radio processing unit 41 Relay control unit 42 Radio resource allocation unit 44. .. Route switching unit 45 .. Line quality sensing unit

Claims (24)

A wireless network is configured by one or more subtrees including subroot stations,
the sub-root station collects requested radio resource allocation information possessed by child stations included in the sub-tree, and receives a sum of the requested radio resource allocation information and the requested radio resource allocation information of the sub-root station itself;
A communication device that notifies the sub-root station of radio resource information available in the entire sub-tree. 2. The communication apparatus according to claim 1, wherein said sub-root station receives said requested radio resource allocation information of said sub-root station itself when said sub-root station does not have a child station. 3. The communication device according to claim 1 or 2, wherein the subtree is configured in each hierarchy of a plurality of hierarchies. 4. The communication apparatus according to any one of claims 1 to 3, wherein the radio resource allocated to each link is divided in the time direction and allocated. 5. The communication apparatus according to any one of claims 1 to 4, wherein the radio resources allocated to the links of the same layer are divided in the frequency direction, and the radio resources allocated to the links of different layers are divided and allocated in the time direction. . 6. The communication apparatus according to any one of claims 1 to 5, wherein the allocation amount of radio resources is changed between upstream and downstream according to the system used. 7. The communication apparatus according to any one of claims 1 to 6, wherein, when there is a new entry station, the sub-root station performs radio resource allocation for the new entry station. calculating the amount of radio resources required for unit data transmission between connectable stations;
calculating the required amount of E2E radio resources between the collection base station and each relay station;
8. The communication device according to any one of claims 1 to 7, wherein a route that minimizes the required radio resource amount obtained is selected. 9. The communication device according to any one of claims 1 to 8, wherein when the established route exceeds the upper limit of the number of connectable stations, the route is reconstructed. 9. The communication apparatus according to claim 8 , wherein when there are a plurality of routes with the minimum amount of required radio resources, the route with the minimum number of hops is selected. 11. The communication device according to claim 10 , wherein when the route with the minimum number of hops cannot be selected, the route with the minimum amount of radio resources required before route change is selected. 12. Of the radio resources received for the subtree from the communication apparatus according to any one of claims 1 to 11, the sub-root station collects the radio resources to be allocated to the sub-root station and the radio resources to be allocated to the slave stations. A communication device that allocates using the absolute value information or ratio information of the requested radio resource amount. A wireless network is configured by one or more subtrees including subroot stations,
the sub-root station collects requested radio resource allocation information possessed by child stations included in the sub-tree, and receives a sum of the requested radio resource allocation information and the requested radio resource allocation information of the sub-root station itself;
A communication method for notifying the sub-root station of radio resource information available in the entire sub-tree. 14. The communication method according to claim 13, wherein said sub-root station receives said requested radio resource allocation information of said sub-root station itself when said sub-root station does not have a child station. 15. The communication method according to claim 13 or 14, wherein said subtree is configured in each hierarchy of a plurality of hierarchies. 16. The communication method according to any one of claims 13 to 15, wherein the radio resource assigned to each link is divided in the time direction and assigned. 17. The communication method according to any one of claims 13 to 16, wherein radio resources allocated to links of the same layer are divided in the frequency direction, and radio resources allocated to links of different layers are divided and allocated in the time direction. . 18. The communication method according to any one of claims 13 to 17, wherein the allocation amount of radio resources is changed between upstream and downstream according to the system used. 19. The communication method according to any one of claims 13 to 18, wherein, when there is a new entrant station, the sub-root station allocates radio resources for the new entrant station. calculating the amount of radio resources required for unit data transmission between connectable stations;
calculating the required amount of E2E radio resources between the collection base station and each relay station;
20. The communication method according to any one of claims 13 to 19, wherein a route that minimizes the required radio resource amount obtained is selected. 21. The communication method according to any one of claims 13 to 20, wherein when the established route exceeds the upper limit of the number of connectable stations, the route is reconstructed. 21. The communication method according to claim 20 , wherein when there are a plurality of routes with the minimum amount of required radio resources, the route with the minimum number of hops is selected. 23. The communication method according to claim 22 , wherein when the route with the minimum number of hops cannot be selected, the route with the minimum required radio resource amount before route change is selected. 24. Of the radio resources received for the sub-tree from the communication method according to any one of claims 13 to 23, the sub-root station collects the radio resources to be allocated to the sub-root station and the radio resources to be allocated to the slave stations. A communication method for allocation using absolute value information or ratio information of requested radio resource amount.

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